refactor: extract shared calculateTotalPages and calculateAvgCostPerPage utilities

- Move duplicated page-counting logic to awsjson-parsers.ts
- Add unit field to CostBreakdownServiceDetail type
- Replace 4 inline copies with single-line utility calls

Author: Taniya Mathur

src/ui/src/components/test-studio/TestComparison.tsx

@@ -20,7 +20,13 @@ import TestStudioHeader from './TestStudioHeader';
 import useLocalStorage from '../common/local-storage';
 import useConfigurationVersions from '../../hooks/use-configuration-versions';
 import { formatConfigVersionLink, formatConfigVersionText, type ConfigVersion as UtilsConfigVersion } from './utils/configVersionUtils';
-import { parseComparisonMetrics, parseWeightedOverallScores, parseConfigSettingValues } from '../../graphql/awsjson-parsers';
+import {
+  parseComparisonMetrics,
+  parseWeightedOverallScores,
+  parseConfigSettingValues,
+  calculateAvgCostPerPage,
+} from '../../graphql/awsjson-parsers';
+import type { CostBreakdown } from '../../graphql/awsjson-types';
 
 const client = generateClient();
 
@@ -305,14 +311,8 @@ const TestComparison = ({ preSelectedTestRunIds = [] }: TestComparisonProps): Re
       [
         'Avg Cost/Page',
         ...Object.values(completeTestRuns).map((run) => {
-          if (run.totalCost == null || !run.costBreakdown) return 'N/A';
-          let totalPages = 0;
-          Object.values(run.costBreakdown as Record<string, Record<string, Record<string, unknown>>>).forEach((services) => {
-            Object.values(services).forEach((details) => {
-              if (details.unit === 'pages') totalPages += Number(details.value) || 0;
-            });
-          });
-          return totalPages > 0 ? `$${(Number(run.totalCost) / totalPages).toFixed(4)}` : 'N/A';
+          const avg = calculateAvgCostPerPage(run.totalCost as number, run.costBreakdown as CostBreakdown);
+          return avg !== null ? `$${avg.toFixed(4)}` : 'N/A';
         }),
       ],
       [
@@ -637,16 +637,7 @@ const TestComparison = ({ preSelectedTestRunIds = [] }: TestComparisonProps): Re
             completedFiles: testRun.completedFiles,
             failedFiles: testRun.failedFiles,
             totalCost: testRun.totalCost,
-            avgCostPerPage: (() => {
-              if (testRun.totalCost == null || !testRun.costBreakdown) return null;
-              let totalPages = 0;
-              Object.values(testRun.costBreakdown as Record<string, Record<string, Record<string, unknown>>>).forEach((services) => {
-                Object.values(services).forEach((details) => {
-                  if (details.unit === 'pages') totalPages += Number(details.value) || 0;
-                });
-              });
-              return totalPages > 0 ? Number(testRun.totalCost) / totalPages : null;
-            })(),
+            avgCostPerPage: calculateAvgCostPerPage(testRun.totalCost as number, testRun.costBreakdown as CostBreakdown),
             averageAccuracy: testRun.overallAccuracy,
             averageConfidence: testRun.averageConfidence,
             averageWeightedOverallScore: (() => {
@@ -845,16 +836,8 @@ const TestComparison = ({ preSelectedTestRunIds = [] }: TestComparisonProps): Re
                   metric: 'Avg Cost/Page',
                   ...Object.fromEntries(
                     Object.entries(completeTestRuns).map(([testRunId, testRun]) => {
-                      if (testRun.totalCost == null || !testRun.costBreakdown) return [testRunId, 'N/A'];
-                      let totalPages = 0;
-                      Object.values(testRun.costBreakdown as Record<string, Record<string, Record<string, unknown>>>).forEach(
-                        (services) => {
-                          Object.values(services).forEach((details) => {
-                            if (details.unit === 'pages') totalPages += Number(details.value) || 0;
-                          });
-                        },
-                      );
-                      return [testRunId, totalPages > 0 ? `$${(Number(testRun.totalCost) / totalPages).toFixed(4)}` : 'N/A'];
+                      const avg = calculateAvgCostPerPage(testRun.totalCost as number, testRun.costBreakdown as CostBreakdown);
+                      return [testRunId, avg !== null ? `$${avg.toFixed(4)}` : 'N/A'];
                     }),
                   ),
                 },

src/ui/src/components/test-studio/TestResults.tsx

@@ -35,6 +35,7 @@ import useAppContext from '../../contexts/app';
 import { formatConfigVersionLink } from './utils/configVersionUtils';
 import {
   parseCostBreakdown,
+  calculateAvgCostPerPage,
   parseAccuracyBreakdown,
   parseSplitClassificationMetrics,
   parseFieldMetrics,
@@ -753,16 +754,7 @@ const TestResults = ({ testRunId, setSelectedTestRunId }: TestResultsProps): Rea
   const costBreakdown: any = results.costBreakdown ? parseCostBreakdown(results.costBreakdown as string) : null;
 
   // Calculate avg cost per page from costBreakdown page counts
-  const avgCostPerPage = (() => {
-    if (results.totalCost == null || !costBreakdown) return null;
-    let totalPages = 0;
-    Object.values(costBreakdown as Record<string, Record<string, Record<string, unknown>>>).forEach((services) => {
-      Object.values(services).forEach((details) => {
-        if (details.unit === 'pages') totalPages += Number(details.value) || 0;
-      });
-    });
-    return totalPages > 0 ? (results.totalCost as number) / totalPages : null;
-  })();
+  const avgCostPerPage = calculateAvgCostPerPage(results.totalCost as number, costBreakdown);
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
   const accuracyBreakdown: any = results.accuracyBreakdown ? parseAccuracyBreakdown(results.accuracyBreakdown as string) : null;
   // eslint-disable-next-line @typescript-eslint/no-explicit-any

src/ui/src/graphql/awsjson-parsers.ts

@@ -58,6 +58,22 @@ export function parseCostBreakdown(json: unknown): CostBreakdown {
   return safeParse<CostBreakdown>(json, {});
 }
 
+export function calculateTotalPages(costBreakdown: CostBreakdown): number {
+  let totalPages = 0;
+  Object.values(costBreakdown).forEach((services) => {
+    Object.values(services).forEach((details) => {
+      if (details.unit === 'pages') totalPages += Number(details.value) || 0;
+    });
+  });
+  return totalPages;
+}
+
+export function calculateAvgCostPerPage(totalCost: number | null | undefined, costBreakdown: CostBreakdown | null): number | null {
+  if (totalCost == null || !costBreakdown) return null;
+  const totalPages = calculateTotalPages(costBreakdown);
+  return totalPages > 0 ? totalCost / totalPages : null;
+}
+
 export function parseTestRunConfig(json: unknown): TestRunConfig | null {
   return safeParse<TestRunConfig | null>(json, null);
 }

src/ui/src/graphql/awsjson-types.ts

@@ -30,6 +30,7 @@ export interface CostBreakdownServiceDetail {
   estimated_cost?: number;
   value?: number;
   unit_cost?: number;
+  unit?: string;
   [key: string]: unknown;
 }